1. Field of the Invention
The present invention relates to an observation apparatus that performs phase difference measurement by using a phase contrast lens.
2. Description of the Related Art
In recent years, broadly using phase difference measurement as a method of observing cultured transparent cells such as stem cells which are unstained has started. In addition, as the apparatus that performs such phase difference measurement, a phase-contrast microscope having a phase contrast lens has been used (for example, refer to JP1990-275918A (JP-H02-275918A)).
Meanwhile, as a method of acquiring a clear microscopic image at a high speed, there have been proposed various super-resolution techniques. As one of those, there has been proposed a method of projecting contrast illumination onto a subject, called a structured illumination technique. Further, as the method of acquiring a microscopic image at a high speed, there has been also proposed a method of projecting structured illumination onto a subject so as to perform detection and confirming a focus position by controlling a position of an objective lens.